1 files changed, 256 insertions, 99 deletions

diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c
index 6a54d2f..590b7e8 100644
--- a/security/apparmor/domain.c
+++ b/security/apparmor/domain.c
@@ -19,10 +19,11 @@
 #include <linux/syscalls.h>
 #include <linux/tracehook.h>
 #include <linux/personality.h>
+#include <linux/xattr.h>
 
 #include "include/audit.h"
 #include "include/apparmorfs.h"
-#include "include/context.h"
+#include "include/cred.h"
 #include "include/domain.h"
 #include "include/file.h"
 #include "include/ipc.h"
@@ -302,7 +303,70 @@ static int change_profile_perms(struct aa_profile *profile,
 }
 
 /**
+ * aa_xattrs_match - check whether a file matches the xattrs defined in profile
+ * @bprm: binprm struct for the process to validate
+ * @profile: profile to match against (NOT NULL)
+ * @state: state to start match in
+ *
+ * Returns: number of extended attributes that matched, or < 0 on error
+ */
+static int aa_xattrs_match(const struct linux_binprm *bprm,
+			   struct aa_profile *profile, unsigned int state)
+{
+	int i;
+	ssize_t size;
+	struct dentry *d;
+	char *value = NULL;
+	int value_size = 0, ret = profile->xattr_count;
+
+	if (!bprm || !profile->xattr_count)
+		return 0;
+
+	/* transition from exec match to xattr set */
+	state = aa_dfa_null_transition(profile->xmatch, state);
+
+	d = bprm->file->f_path.dentry;
+
+	for (i = 0; i < profile->xattr_count; i++) {
+		size = vfs_getxattr_alloc(d, profile->xattrs[i], &value,
+					  value_size, GFP_KERNEL);
+		if (size >= 0) {
+			u32 perm;
+
+			/* Check the xattr value, not just presence */
+			state = aa_dfa_match_len(profile->xmatch, state, value,
+						 size);
+			perm = dfa_user_allow(profile->xmatch, state);
+			if (!(perm & MAY_EXEC)) {
+				ret = -EINVAL;
+				goto out;
+			}
+		}
+		/* transition to next element */
+		state = aa_dfa_null_transition(profile->xmatch, state);
+		if (size < 0) {
+			/*
+			 * No xattr match, so verify if transition to
+			 * next element was valid. IFF so the xattr
+			 * was optional.
+			 */
+			if (!state) {
+				ret = -EINVAL;
+				goto out;
+			}
+			/* don't count missing optional xattr as matched */
+			ret--;
+		}
+	}
+
+out:
+	kfree(value);
+	return ret;
+}
+
+/**
  * __attach_match_ - find an attachment match
+ * @bprm - binprm structure of transitioning task
  * @name - to match against  (NOT NULL)
  * @head - profile list to walk  (NOT NULL)
  * @info - info message if there was an error (NOT NULL)
@@ -316,40 +380,80 @@ static int change_profile_perms(struct aa_profile *profile,
  *
  * Returns: profile or NULL if no match found
  */
-static struct aa_profile *__attach_match(const char *name,
+static struct aa_profile *__attach_match(const struct linux_binprm *bprm,
+					 const char *name,
 					 struct list_head *head,
 					 const char **info)
 {
-	int len = 0;
+	int candidate_len = 0, candidate_xattrs = 0;
 	bool conflict = false;
 	struct aa_profile *profile, *candidate = NULL;
 
+	AA_BUG(!name);
+	AA_BUG(!head);
+
 	list_for_each_entry_rcu(profile, head, base.list) {
 		if (profile->label.flags & FLAG_NULL &&
 		    &profile->label == ns_unconfined(profile->ns))
 			continue;
 
+		/* Find the "best" matching profile. Profiles must
+		 * match the path and extended attributes (if any)
+		 * associated with the file. A more specific path
+		 * match will be preferred over a less specific one,
+		 * and a match with more matching extended attributes
+		 * will be preferred over one with fewer. If the best
+		 * match has both the same level of path specificity
+		 * and the same number of matching extended attributes
+		 * as another profile, signal a conflict and refuse to
+		 * match.
+		 */
 		if (profile->xmatch) {
-			if (profile->xmatch_len >= len) {
-				unsigned int state;
-				u32 perm;
-
-				state = aa_dfa_match(profile->xmatch,
-						     DFA_START, name);
-				perm = dfa_user_allow(profile->xmatch, state);
-				/* any accepting state means a valid match. */
-				if (perm & MAY_EXEC) {
-					if (profile->xmatch_len == len) {
+			unsigned int state, count;
+			u32 perm;
+
+			state = aa_dfa_leftmatch(profile->xmatch, DFA_START,
+						 name, &count);
+			perm = dfa_user_allow(profile->xmatch, state);
+			/* any accepting state means a valid match. */
+			if (perm & MAY_EXEC) {
+				int ret;
+
+				if (count < candidate_len)
+					continue;
+
+				ret = aa_xattrs_match(bprm, profile, state);
+				/* Fail matching if the xattrs don't match */
+				if (ret < 0)
+					continue;
+
+				/*
+				 * TODO: allow for more flexible best match
+				 *
+				 * The new match isn't more specific
+				 * than the current best match
+				 */
+				if (count == candidate_len &&
+				    ret <= candidate_xattrs) {
+					/* Match is equivalent, so conflict */
+					if (ret == candidate_xattrs)
 						conflict = true;
-						continue;
-					}
-					candidate = profile;
-					len = profile->xmatch_len;
-					conflict = false;
+					continue;
 				}
+
+				/* Either the same length with more matching
+				 * xattrs, or a longer match
+				 */
+				candidate = profile;
+				candidate_len = profile->xmatch_len;
+				candidate_xattrs = ret;
+				conflict = false;
 			}
 		} else if (!strcmp(profile->base.name, name))
-			/* exact non-re match, no more searching required */
+			/*
+			 * old exact non-re match, without conditionals such
+			 * as xattrs. no more searching required
+			 */
 			return profile;
 	}
 
@@ -363,6 +467,7 @@ static struct aa_profile *__attach_match(const char *name,
 
 /**
  * find_attach - do attachment search for unconfined processes
+ * @bprm - binprm structure of transitioning task
  * @ns: the current namespace  (NOT NULL)
  * @list: list to search  (NOT NULL)
  * @name: the executable name to match against  (NOT NULL)
@@ -370,13 +475,14 @@ static struct aa_profile *__attach_match(const char *name,
  *
  * Returns: label or NULL if no match found
  */
-static struct aa_label *find_attach(struct aa_ns *ns, struct list_head *list,
+static struct aa_label *find_attach(const struct linux_binprm *bprm,
+				    struct aa_ns *ns, struct list_head *list,
 				    const char *name, const char **info)
 {
 	struct aa_profile *profile;
 
 	rcu_read_lock();
-	profile = aa_get_profile(__attach_match(name, list, info));
+	profile = aa_get_profile(__attach_match(bprm, name, list, info));
 	rcu_read_unlock();
 
 	return profile ? &profile->label : NULL;
@@ -432,6 +538,7 @@ struct aa_label *x_table_lookup(struct aa_profile *profile, u32 xindex,
 /**
  * x_to_label - get target label for a given xindex
  * @profile: current profile  (NOT NULL)
+ * @bprm: binprm structure of transitioning task
  * @name: name to lookup (NOT NULL)
  * @xindex: index into x transition table
  * @lookupname: returns: name used in lookup if one was specified (NOT NULL)
@@ -441,6 +548,7 @@ struct aa_label *x_table_lookup(struct aa_profile *profile, u32 xindex,
  * Returns: refcounted label or NULL if not found available
  */
 static struct aa_label *x_to_label(struct aa_profile *profile,
+				   const struct linux_binprm *bprm,
 				   const char *name, u32 xindex,
 				   const char **lookupname,
 				   const char **info)
@@ -468,11 +576,11 @@ static struct aa_label *x_to_label(struct aa_profile *profile,
 	case AA_X_NAME:
 		if (xindex & AA_X_CHILD)
 			/* released by caller */
-			new = find_attach(ns, &profile->base.profiles,
+			new = find_attach(bprm, ns, &profile->base.profiles,
 					  name, info);
 		else
 			/* released by caller */
-			new = find_attach(ns, &ns->base.profiles,
+			new = find_attach(bprm, ns, &ns->base.profiles,
 					  name, info);
 		*lookupname = name;
 		break;
@@ -512,6 +620,8 @@ static struct aa_label *profile_transition(struct aa_profile *profile,
 					   bool *secure_exec)
 {
 	struct aa_label *new = NULL;
+	struct aa_profile *component;
+	struct label_it i;
 	const char *info = NULL, *name = NULL, *target = NULL;
 	unsigned int state = profile->file.start;
 	struct aa_perms perms = {};
@@ -536,8 +646,8 @@ static struct aa_label *profile_transition(struct aa_profile *profile,
 	}
 
 	if (profile_unconfined(profile)) {
-		new = find_attach(profile->ns, &profile->ns->base.profiles,
-				  name, &info);
+		new = find_attach(bprm, profile->ns,
+				  &profile->ns->base.profiles, name, &info);
 		if (new) {
 			AA_DEBUG("unconfined attached to new label");
 			return new;
@@ -550,7 +660,8 @@ static struct aa_label *profile_transition(struct aa_profile *profile,
 	state = aa_str_perms(profile->file.dfa, state, name, cond, &perms);
 	if (perms.allow & MAY_EXEC) {
 		/* exec permission determine how to transition */
-		new = x_to_label(profile, name, perms.xindex, &target, &info);
+		new = x_to_label(profile, bprm, name, perms.xindex, &target,
+				 &info);
 		if (new && new->proxy == profile->label.proxy && info) {
 			/* hack ix fallback - improve how this is detected */
 			goto audit;
@@ -559,6 +670,21 @@ static struct aa_label *profile_transition(struct aa_profile *profile,
 			info = "profile transition not found";
 			/* remove MAY_EXEC to audit as failure */
 			perms.allow &= ~MAY_EXEC;
+		} else {
+			/* verify that each component's xattr requirements are
+			 * met, and fail execution otherwise
+			 */
+			label_for_each(i, new, component) {
+				if (aa_xattrs_match(bprm, component, state) <
+				    0) {
+					error = -EACCES;
+					info = "required xattrs not present";
+					perms.allow &= ~MAY_EXEC;
+					aa_put_label(new);
+					new = NULL;
+					goto audit;
+				}
+			}
 		}
 	} else if (COMPLAIN_MODE(profile)) {
 		/* no exec permission - learning mode */
@@ -592,22 +718,6 @@ static struct aa_label *profile_transition(struct aa_profile *profile,
 	if (!new)
 		goto audit;
 
-	/* Policy has specified a domain transitions. if no_new_privs and
-	 * confined and not transitioning to the current domain fail.
-	 *
-	 * NOTE: Domain transitions from unconfined and to stritly stacked
-	 * subsets are allowed even when no_new_privs is set because this
-	 * aways results in a further reduction of permissions.
-	 */
-	if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) &&
-	    !profile_unconfined(profile) &&
-	    !aa_label_is_subset(new, &profile->label)) {
-		error = -EPERM;
-		info = "no new privs";
-		nonewprivs = true;
-		perms.allow &= ~MAY_EXEC;
-		goto audit;
-	}
 
 	if (!(perms.xindex & AA_X_UNSAFE)) {
 		if (DEBUG_ON) {
@@ -684,21 +794,6 @@ static int profile_onexec(struct aa_profile *profile, struct aa_label *onexec,
 		perms.allow &= ~AA_MAY_ONEXEC;
 		goto audit;
 	}
-	/* Policy has specified a domain transitions. if no_new_privs and
-	 * confined and not transitioning to the current domain fail.
-	 *
-	 * NOTE: Domain transitions from unconfined and to stritly stacked
-	 * subsets are allowed even when no_new_privs is set because this
-	 * aways results in a further reduction of permissions.
-	 */
-	if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) &&
-	    !profile_unconfined(profile) &&
-	    !aa_label_is_subset(onexec, &profile->label)) {
-		error = -EPERM;
-		info = "no new privs";
-		perms.allow &= ~AA_MAY_ONEXEC;
-		goto audit;
-	}
 
 	if (!(perms.xindex & AA_X_UNSAFE)) {
 		if (DEBUG_ON) {
@@ -794,10 +889,22 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm)
 	if (bprm->called_set_creds)
 		return 0;
 
-	ctx = cred_ctx(bprm->cred);
+	ctx = task_ctx(current);
+	AA_BUG(!cred_label(bprm->cred));
 	AA_BUG(!ctx);
 
-	label = aa_get_newest_label(ctx->label);
+	label = aa_get_newest_label(cred_label(bprm->cred));
+
+	/*
+	 * Detect no new privs being set, and store the label it
+	 * occurred under. Ideally this would happen when nnp
+	 * is set but there isn't a good way to do that yet.
+	 *
+	 * Testing for unconfined must be done before the subset test
+	 */
+	if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) && !unconfined(label) &&
+	    !ctx->nnp)
+		ctx->nnp = aa_get_label(label);
 
 	/* buffer freed below, name is pointer into buffer */
 	get_buffers(buffer);
@@ -819,7 +926,20 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm)
 		goto done;
 	}
 
-	/* TODO: Add ns level no_new_privs subset test */
+	/* Policy has specified a domain transitions. If no_new_privs and
+	 * confined ensure the transition is to confinement that is subset
+	 * of the confinement when the task entered no new privs.
+	 *
+	 * NOTE: Domain transitions from unconfined and to stacked
+	 * subsets are allowed even when no_new_privs is set because this
+	 * aways results in a further reduction of permissions.
+	 */
+	if ((bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) &&
+	    !unconfined(label) && !aa_label_is_subset(new, ctx->nnp)) {
+		error = -EPERM;
+		info = "no new privs";
+		goto audit;
+	}
 
 	if (bprm->unsafe & LSM_UNSAFE_SHARE) {
 		/* FIXME: currently don't mediate shared state */
@@ -853,14 +973,11 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm)
 		}
 		bprm->per_clear |= PER_CLEAR_ON_SETID;
 	}
-	aa_put_label(ctx->label);
-	/* transfer reference, released when ctx is freed */
-	ctx->label = new;
+	aa_put_label(cred_label(bprm->cred));
+	/* transfer reference, released when cred is freed */
+	cred_label(bprm->cred) = new;
 
 done:
-	/* clear out temporary/transitional state from the context */
-	aa_clear_task_ctx_trans(ctx);
-
 	aa_put_label(label);
 	put_buffers(buffer);
 
@@ -1049,30 +1166,28 @@ build:
 int aa_change_hat(const char *hats[], int count, u64 token, int flags)
 {
 	const struct cred *cred;
-	struct aa_task_ctx *ctx;
+	struct aa_task_ctx *ctx = task_ctx(current);
 	struct aa_label *label, *previous, *new = NULL, *target = NULL;
 	struct aa_profile *profile;
 	struct aa_perms perms = {};
 	const char *info = NULL;
 	int error = 0;
 
-	/*
-	 * Fail explicitly requested domain transitions if no_new_privs.
-	 * There is no exception for unconfined as change_hat is not
-	 * available.
-	 */
-	if (task_no_new_privs(current)) {
-		/* not an apparmor denial per se, so don't log it */
-		AA_DEBUG("no_new_privs - change_hat denied");
-		return -EPERM;
-	}
-
 	/* released below */
 	cred = get_current_cred();
-	ctx = cred_ctx(cred);
 	label = aa_get_newest_cred_label(cred);
 	previous = aa_get_newest_label(ctx->previous);
 
+	/*
+	 * Detect no new privs being set, and store the label it
+	 * occurred under. Ideally this would happen when nnp
+	 * is set but there isn't a good way to do that yet.
+	 *
+	 * Testing for unconfined must be done before the subset test
+	 */
+	if (task_no_new_privs(current) && !unconfined(label) && !ctx->nnp)
+		ctx->nnp = aa_get_label(label);
+
 	if (unconfined(label)) {
 		info = "unconfined can not change_hat";
 		error = -EPERM;
@@ -1093,6 +1208,18 @@ int aa_change_hat(const char *hats[], int count, u64 token, int flags)
 		if (error)
 			goto fail;
 
+		/*
+		 * no new privs prevents domain transitions that would
+		 * reduce restrictions.
+		 */
+		if (task_no_new_privs(current) && !unconfined(label) &&
+		    !aa_label_is_subset(new, ctx->nnp)) {
+			/* not an apparmor denial per se, so don't log it */
+			AA_DEBUG("no_new_privs - change_hat denied");
+			error = -EPERM;
+			goto out;
+		}
+
 		if (flags & AA_CHANGE_TEST)
 			goto out;
 
@@ -1102,6 +1229,18 @@ int aa_change_hat(const char *hats[], int count, u64 token, int flags)
 			/* kill task in case of brute force attacks */
 			goto kill;
 	} else if (previous && !(flags & AA_CHANGE_TEST)) {
+		/*
+		 * no new privs prevents domain transitions that would
+		 * reduce restrictions.
+		 */
+		if (task_no_new_privs(current) && !unconfined(label) &&
+		    !aa_label_is_subset(previous, ctx->nnp)) {
+			/* not an apparmor denial per se, so don't log it */
+			AA_DEBUG("no_new_privs - change_hat denied");
+			error = -EPERM;
+			goto out;
+		}
+
 		/* Return to saved label.  Kill task if restore fails
 		 * to avoid brute force attacks
 		 */
@@ -1144,21 +1283,6 @@ static int change_profile_perms_wrapper(const char *op, const char *name,
 	const char *info = NULL;
 	int error = 0;
 
-	/*
-	 * Fail explicitly requested domain transitions when no_new_privs
-	 * and not unconfined OR the transition results in a stack on
-	 * the current label.
-	 * Stacking domain transitions and transitions from unconfined are
-	 * allowed even when no_new_privs is set because this aways results
-	 * in a reduction of permissions.
-	 */
-	if (task_no_new_privs(current) && !stack &&
-	    !profile_unconfined(profile) &&
-	    !aa_label_is_subset(target, &profile->label)) {
-		info = "no new privs";
-		error = -EPERM;
-	}
-
 	if (!error)
 		error = change_profile_perms(profile, target, stack, request,
 					     profile->file.start, perms);
@@ -1192,10 +1316,23 @@ int aa_change_profile(const char *fqname, int flags)
 	const char *info = NULL;
 	const char *auditname = fqname;		/* retain leading & if stack */
 	bool stack = flags & AA_CHANGE_STACK;
+	struct aa_task_ctx *ctx = task_ctx(current);
 	int error = 0;
 	char *op;
 	u32 request;
 
+	label = aa_get_current_label();
+
+	/*
+	 * Detect no new privs being set, and store the label it
+	 * occurred under. Ideally this would happen when nnp
+	 * is set but there isn't a good way to do that yet.
+	 *
+	 * Testing for unconfined must be done before the subset test
+	 */
+	if (task_no_new_privs(current) && !unconfined(label) && !ctx->nnp)
+		ctx->nnp = aa_get_label(label);
+
 	if (!fqname || !*fqname) {
 		AA_DEBUG("no profile name");
 		return -EINVAL;
@@ -1283,14 +1420,28 @@ check:
 	if (flags & AA_CHANGE_TEST)
 		goto out;
 
+	/* stacking is always a subset, so only check the nonstack case */
+	if (!stack) {
+		new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
+					   aa_get_label(target),
+					   aa_get_label(&profile->label));
+		/*
+		 * no new privs prevents domain transitions that would
+		 * reduce restrictions.
+		 */
+		if (task_no_new_privs(current) && !unconfined(label) &&
+		    !aa_label_is_subset(new, ctx->nnp)) {
+			/* not an apparmor denial per se, so don't log it */
+			AA_DEBUG("no_new_privs - change_hat denied");
+			error = -EPERM;
+			goto out;
+		}
+	}
+
 	if (!(flags & AA_CHANGE_ONEXEC)) {
 		/* only transition profiles in the current ns */
 		if (stack)
 			new = aa_label_merge(label, target, GFP_KERNEL);
-		else
-			new = fn_label_build_in_ns(label, profile, GFP_KERNEL,
-					aa_get_label(target),
-					aa_get_label(&profile->label));
 		if (IS_ERR_OR_NULL(new)) {
 			info = "failed to build target label";
 			error = PTR_ERR(new);
@@ -1299,9 +1450,15 @@ check:
 			goto audit;
 		}
 		error = aa_replace_current_label(new);
-	} else
+	} else {
+		if (new) {
+			aa_put_label(new);
+			new = NULL;
+		}
+
 		/* full transition will be built in exec path */
 		error = aa_set_current_onexec(target, stack);
+	}
 
 audit:
 	error = fn_for_each_in_ns(label, profile,